Nitrile-butadiene rubber (NBR) is an oil resistant elastomer used in automotive applications. It has poor high temperature properties. The recommended continuous use temperature is between 100.degree.-125.degree. C. Commercially available hydrogenated NBR (HNBR) addresses the need for a higher use temperature, oil resistant elastomer having a continuous use temperature up to about 150.degree. C.
Removal of the backbone unsaturation in NBR by hydrogenation increases the heat resistance of the polymer while maintaining its low temperature and oil resistance properties. HNBR is mainly a random copolymer of ethylene and acrylonitrile. HNBR compositions that contain up to 40 weight percent bound acrylonitrile and 60 weight percent hydrocarbon segments have high oil resistance and good low temperature properties. Higher acrylonitrile content in the copolymer would further increase oil resistance, but would be detrimental to low temperature properties.
U.S. Pat. No. 3,416,899 (Schiff, Dec. 17, 1968) relates to improved gel compositions useful as incendiary fuels, as solid fuels for heating, as a fracturing liquid for subterranean formations, and the like. In another aspect, this reference relates to the preparation of hydrocarbon gel compositions by hydrogenating a hydrocarbon solution of an unsaturated rubbery polymer in the presence of a catalyst comprising a reducing metal compound and a salt of a Group VIII metal.
U.S. Pat. No. 3,766,300 (De La Mare, Oct. 16, 1973) discloses a process for the hydrogenation of copolymers prepared from conjugated dienes and certain copolymerizable polar monomers such as vinyl pyridines, acrylonitriles, and alpha-olefin oxides which comprises an initial step of forming a complex between at least one Lewis acid and the polar portions of the copolymer and thereafter subjecting the complex to hydrogenation. More particularly, this reference is especially concerned with a process for the hydrogenation of block copolymers derived from these monomers.
Japanese Patent No. 13,615 (Aug. 2, 1967; filed Feb. 15, 1963) relates to copolymers of butadiene and vinyl pyridine that were reduced to give waterproof, stable reduced copolymers. These products were useful for coating pills. The reduced copolymers were obtained by the catalytic hydrogenation in the presence of Raney nickel catalyst.
A paper titled "Oil-Resistant Rubbers from 2-Methyl Vinyl Pyridine," James E. Pritchard and Milton H. Opheim, Industrial and Engineering Chemistry, Volume 46, No. 10, pages 2242-2245, relates to quaternization of liquid polymers. Copolymers of butadiene and 2-methyl-5-vinyl pyridine (MVP) react with quaternizing agents to form polymeric salts of the type: ##STR2## where R is an aliphatic or aromatic radical and X represents halide, alkyl sulfate, or aryl sulfonate groups.